Sen. Blanche Lincoln survived a bitter Democratic runoff Tuesday in Arkansas, fending off a strong challenge from labor-backed Lt. Gov. Bill Halter to avoid becoming the third senator this year to lose a bid for reelection.

In a year of voter anger that has put incumbents in both parties on the defensive, Lincoln battled back against organized labor and progressive groups that had targeted her for defeat, salvaging her nomination for a third term. She was one of several women from both political parties to emerge victorious on a "Super Duper Tuesday" of primaries that included gains by "tea party" candidates in some states but also survival of incumbents in others, and that overall did not provide a uniform storyline about the nation's political mood.

On the busiest election day so far this year, 12 states -- including Virginia-- held primaries, with major contests in Arkansas, California, Nevada and South Carolina.

In California, two businesswomen who built their campaigns around their personal fortunes and strong conservative credentials won hard-fought GOP nomination contests for governor and a U.S. Senate seat. In the gubernatorial primary, former eBay chief executive Meg Whitman easily defeated state Insurance Commissioner Steve Poizner after spending nearly $80 million, much of it her own money. She will face state Attorney General Edmund G. "Jerry" Brown Jr., who served two terms as governor three decades ago, in what is expected to be one of the costliest and most competitive contests this fall.

California Republicans also nominated former Hewlett-Packard chief executive Carly Fiorina to take on Sen. Barbara Boxer (D), whose lackluster poll ratings have made her appear vulnerable in November. Fiorina defeated former congressman Tom Campbell and state Assemblyman Chuck DeVore.

Nevada Gov. Jim Gibbons (R), whose tenure has been marred by personal scandal and a nasty divorce and who became an outcast in his party, lost to former U.S. district judge Brian Sandoval. He is the first governor in the state's history to be denied renomination and the first sitting governor to lose in a primary since Sarah Palin defeated Frank Murkowski in Alaska in 2006. Democrats nominated Rory Reid, chairman of the Clark County Commission and the son of Harry Reid, to challenge Sandoval.

Meanwhile, in South Carolina, state Rep. Nikki Haley ran far ahead of her three male rivals for the Republican gubernatorial nomination with 49 percent of the vote. But she fell just short of the 50 percent needed to avoid a June 22 runoff. She will face Rep. J. Gresham Barrett, who captured about 22 percent, in the runoff.

The gubernatorial primary stamped the Palmetto State once again as ground zero for dirty politics. Haley was the subject of unsubstantiated allegations of marital infidelity and a racial slur -- all after she began rising in the polls. She denied the allegations and gathered strength in the campaign's final days.

The winner of the South Carolina runoff will face state Sen. Vincent Sheheen.

One race Tuesday, in Georgia, produced a new member of Congress: Former state representative Tom Graves (R) easily defeated former state senator Lee Hawkins (R) in a special House election to fill the former seat of Nathan Deal, who resigned to run for governor.

But most of the attention Tuesday was focused on Arkansas, and Lincoln's fight for survival. The centrist senator finished narrowly ahead of Halter in the first round of voting on May 18 and was on the defensive throughout the runoff campaign. Unions vowed to make an example of her after she did not support the "public option" during the health-care debate. She also opposed a union-backed bill designed to make it easier for workers to organize -- one of labor's top priorities.

Unions pitched in nearly $10 million to try to defeat her. But with the help of former president Bill Clinton, Lincoln challenged them and sought to assure voters that she understands their anger at Washington. Clinton, an Arkansas native, challenged voters not to be used by the unions. He campaigned in the state and was featured in one of Lincoln's final television commercials.

Although she also had the support of President Obama, he played a minimal role in the race.

With nearly all the vote counted, Lincoln had 52 percent to Halter's 48 percent. She will now face an equally difficult general election campaign against Rep. John Boozman, who won the May 18 Republican primary.

Lincoln was not the only endangered southern incumbent Tuesday. In South Carolina, Rep. Bob Inglis (R) was forced into a runoff against prosecutor Trey Gowdy, who had a strong lead but was short of the 50 percent needed to win the primary without a runoff. Inglis's support for the federal government's bank bailout put his seat in jeopardy and he will face an uphill fight in the June 22 runoff.

Already this year two senators, Republican-turned-Democrat Arlen Specter (Pa.) and Republican Robert F. Bennett (Utah), were defeated in their reelection bids. Two House lawmakers, Democrat Alan B. Mollohan (W.Va.) and Democrat-turned-Republican Parker Griffith (Miss.), also lost their primaries.

Tea party effect

The Nevada Republican Senate primary was closely watched because Republicans are determined to defeat Reid in November, and for much of this year he has appeared highly vulnerable. The question was whether GOP voters would nominate the strongest candidate to challenge him.

Angle, who had the backing of tea party activists and the Club for Growth, was a distinct underdog when the race began but was the clear favorite by Election Day.

Her victory marks another major milestone for the loosely organized protest movement that has shaken up politics this year. Three weeks ago, GOP voters in Kentucky upset the establishment by nominating libertarian-conservative and tea party favorite Rand Paul for the open Senate seat there.

But some have questioned whether Angle is too conservative for Nevada. She has called for the elimination of several federal agencies, including the departments of Education and Energy. She also favors using Yucca Mountain as a permanent storage site for nuclear waste, a position opposed by politicians in both parties in the state.

Lowden was the early front-runner. But she stumbled badly during the campaign, with the pivotal moment coming when she talked about bartering chickens for health care. She was also targeted by television ads paid for by allies of Reid, who considered her his strongest potential challenger.

Major races

California, the nation's most populous state, featured two of the most important Republican primaries Tuesday.

In the Senate contest, Fiorina faced Campbell and DeVore.

The campaign devolved into a debate about who was best positioned to defeat Boxer in November. Campbell, who is conservative on fiscal issues and moderate on social issues, argued that he would make the stronger general-election candidate.

Fiorina, who is conservative on economic and social issues and won the support of former Alaska governor Sarah Palin (R), argued that her outsider appeal, business background and aggressive campaign style would give her the advantage against Boxer. With the help of her own bank account, Fiorina outspent her opponents in the final weeks.

The Republican gubernatorial primary campaign between Whitman and Poizner was far more contentious, and it involved spending rarely seen in primary campaigns. Whitman, a billionaire, surged to a huge lead over Poizner in the early months of the year, backed by tens of millions in spending, most of it from her personal account. Her lead was estimated at 40 to 50 percentage points.

Poizner, who was a Silicon Valley entrepreneur before entering politics, spent about $24 million of his own money on tough ads that temporarily narrowed her lead. She counterattacked and surged to victory.